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10/24/2017 – Ephemeris – Saturn and the Moon tonight

October 24, 2017 1 comment

Ephemeris for Tuesday, October 24th. The Sun will rise at 8:09. It’ll be up for 10 hours and 32 minutes, setting at 6:42. The Moon, 3 days before first quarter, will set at 10:09 this evening.

The crescent Moon will be in the southwest as it gets dark tonight. The planet Saturn will appear below and to the right of our satellite. Saturn has those gorgeous rings, which are visible at as low as 20 power scopes and hinted at lower magnifications. The Moon shows a fat crescent with two whole gray seas, Crises, nearest the limb, and below Fertility. Partially illuminated are Tranquility above and the small sea of Nectar. At the bottom end of that small sea is a horse shoe shaped crater called Fracastorius. It looks like the lava welling up from the Nectar asteroid impact washed down the walls of Fracastorius. The bottom part of the Moon is the lunar highlands of brighter rugged craters.

The times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.

Addendum

The Moon and Saturn

The Moon and Saturn at 8 p.m. October 24, 2017. Created using Stellarium.

Binocular Moon

The Moon at 8 p.m. October 24, 2017 as it might be seen in binoculars. Created using Virtual Moon Atlas.

 

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09/26/2017 – Ephemeris – Saturn appears near the Moon tonight

September 26, 2017 1 comment

Ephemeris for Tuesday, September 26th. The Sun will rise at 7:34. It’ll be up for 11 hours and 57 minutes, setting at 7:31. The Moon, 1 day before first quarter, will set at 11:32 this evening.

Tonight the Moon will to be near the planet Saturn. At 9 p.m. the ringed planet will be seen below the crescent Moon. It’s a good way to spot Saturn if you’ve never be able to figure out which of those “stars” in the sky is Saturn. It’s easy to confirm with a small telescope. Even in binoculars Saturn is not quite a star-like point. Saturn’s rings begin to show distinctly with 20 power magnification. The Moon too is great to view at low power, even binoculars. A new sea has appeared since last night. It is the Sea of Serenity above the center of the Moon. The lunar seas are really large nearly circular lava filled craters that appear to have been the result of asteroid impacts about 3.8 or so billion years ago.

The times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.

Addendum

Saturn and the Moon

Saturn and the Moon tonight, 9 p.m. September 26, 2017. Created using Stellarium.

Binocular Moon

The Moon as it might be seen in binoculars, 9 p.m. September 26, 2017. Created using Stellarium.

Compare with last night’s Moon.

The Moon tonight

The annotated crescent moon tonight, September 25, 2017. Created using Virtual Moon Atlas.

09/04/2017 – Ephemeris – Cassini has only 11 days to go.

September 4, 2017 Comments off

Ephemeris for Labor Day, Monday, September 4th. The Sun will rise at 7:08. It’ll be up for 13 hours and 4 minutes, setting at 8:13. The Moon, 2 days before full, will set at 6:16 tomorrow morning.

In 11 days, the school bus sized Cassini spacecraft, which has orbited Saturn for the last 13 years will make it’s final plunge into Saturn’s atmosphere to burn up. Cassini’s controllers at the Jet Propulsion Laboratory decided after finding the small moon Enceladus had an internal ocean that it was venting into space with interesting compounds, that it could possibly harbor life, so leaving Cassini derelict orbiting Saturn among the moons, was thought not to be a good idea, in case the unsterilized spacecraft were to crash into Enceladus. So since this spring Cassini was directed to make a series of orbits that took it inside the rings, and on the final orbit to plunge into Saturn’s atmosphere to burn up.

The times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.

Addendum

Cassini Flying between the planet and the rings.

An artist’s visualization of Cassini Flying between the planet and the rings. Credit NASA/JPL.  Click on the image to enlarge.

07/06/2017 – Ephemeris – Saturn will appear near the Moon tonight

July 6, 2017 1 comment

Ephemeris for Thursday, July 6th. Today the Sun will be up for 15 hours and 25 minutes, setting at 9:29, and it will rise tomorrow at 6:05. The Moon, 3 days before full, will set at 5:02 tomorrow morning.

The waxing gibbous Moon and the planet Saturn will appear together tonight. They are said to be in conjunction. The brightness of the Moon may make it hard to pick out Saturn which is right under the Moon by about seven Moon diameters. The Moon is very bright in binoculars or a telescope and looking at it destroys the dark adaption in the eye or eyes that look at it, at least for a while. So when viewing both Saturn and the Moon, concentrate of Saturn first. In a telescope Saturn’s rings are glorious. With a good telescope and enough magnification one might see the split in the rings, just inside the outer edge of them called Cassini’s Division, after it’s discoverer. The large moon Titan is off the western extremity of the rings tonight.

The times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.

Addendum

 

Saturn and the Moon

The Moon and Saturn at 10:30 p.m., July 6, 2017, as it would be seen from northern Michigan. Created using Stellarium.

Saturn showing Cassini's Division

Saturn and its rings with Cassini’s Division. Created using Stellarium.

Ring particles at the distance of Cassini’s Division from Saturn orbit the planet twice in the time the satellite Mimas, nicknamed the Death Star, orbits the planet once.  Ring particles are thus tugged by Mimas’ gravity away from Saturn in the same place every other orbit, which pulls them out of that particular orbital resonance.

Mimas

“That’s no moon!” Yes it is. Saturn’s moon Mimas, It’s diameter is 123 miles (198 km). The huge crater is named Herschel, after the moon’s discoverer William Herschel. Credit: NASA / JPL-Caltech / Space Science Institute.

06/15/2017 – Ephemeris – Saturn is at opposition from the Sun today

June 15, 2017 1 comment

Ephemeris for Thursday, June 15th. Today the Sun will be up for 15 hours and 32 minutes, setting at 9:29, and it will rise tomorrow at 5:56. The Moon, 2 days before last quarter, will rise at 1:28 tomorrow morning.

The Planet Saturn was in opposition with the Sun at 5:15 (09:15 UT) this morning. That means that it was 180 degrees from the Sun, well 178.6 degrees to be exact, because the Earth is a bit south of the Sun-Saturn line. This is a time when the shadows of the rings on the planet and planet on the rings almost disappear, due to our vantage point. Saturn is also closest now at 842 million miles (1.356 billion km). It average distance being about 940 million miles (1.5 billion km). In three months our emissary to Saturn, the Cassini spacecraft will dive beneath Saturn’s clouds to burn up after using up almost all its maneuvering fuel. Then we with our telescopes on and around Earth will remain the only link to the ringed planet.

The times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.

Addendum

Saturn at opposition

Saturn at opposition in a perspective view of the solar system which compresses the fact that Saturn is 10 times farther from the Sun as the Earth. Created using my LookingUp program.

06/12/2017 – Ephemeris – Now is a great time to view Saturn

June 12, 2017 Comments off

Ephemeris for Monday, June 12th. Today the Sun will be up for 15 hours and 31 minutes, setting at 9:28, and it will rise tomorrow at 5:56. The Moon, 3 days past full, will rise at 11:44 this evening.

In three days the planet Saturn will be opposite the Sun in the sky. Astronomers simply call it opposition. It’s the time Saturn will be closest to us, and appear biggest in telescopes. That’s not a big a deal as for a closer, smaller planet like Mars or Venus. Being ten times farther from the Sun than the Earth Saturn’s distance and thus it’s size varies by only plus or minus 10%. Another event happened on Saturn last month, Summer started in it’s northern hemisphere. Saturn’s rings orbit the planet over it’s equator, and Saturn’s axial tilt of obliquity is 26 degrees, similar to the Earth’s actually. This summer solstice means that the rings are at their most open because we are viewing Saturn from near the Sun, so a first glance through a telescope Saturn looks elliptical, with the planetary ball completely within the rings.

The times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.

Addendum

Saturn's Rings over time

Saturn’s Rings over time as they closed. Credit NASA/HST/WFPC2

Now the rings are opened to their maximum extent with the northern hemisphere of Saturn uncovered by the rings and the southern hemisphere covered by them, the reverse of the top image.

Categories: Ephemeris Program, Saturn

05/11/2017 – Ephemeris – Cassini is surviving its death-defying dives under the rings of Saturn

May 11, 2017 Comments off

Ephemeris for Thursday, May 11th.  Today the Sun will be up for 14 hours and 40 minutes, setting at 8:59, and it will rise tomorrow at 6:17.  The Moon, 1 day past full, will rise at 9:42 this evening.

The Cassini spacecraft has been redirected by passing Titan on a special trajectory that sent it into a fatal set of orbits that take it a few thousand miles above Saturn’s cloud tops and under the innermost rings.  So far after two passes Cassini survives.  One discovery of the first pass was a storm, perhaps a hurricane, whose clear eye is at Saturn’s north pole.  Cassini has yet to turn its cameras to the rings on these passes inside the rings, but it will before its final orbit.  Currently it is flying communication dish first to protect its delicate instruments from ring particles.  So far the gap between the rings and the planet are more free of particles than expected.  Which is a good omen for the last 20 passes between the rings and planet.

The times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.

Addendum

Cassini's grand finale

In its planned last 22 orbits of Saturn, the Cassini spacecraft will pass between the innermost ring and the planet itself. Credit NASA, JPL.

Saturn's North Pole

The clearing (blue sky) in the clouds at Saturn’s north pole spotted by Cassini on its first pass under the rings. Credit: NASA/JPL-Cal Tech/S Si/Sophia Nasr